1. Field of the Invention
The present invention relates to a pipetting device for automatic injection of minute volumes of a solution which is used in an apparatus for automatically and continuously measuring a number of (solution) samples, and more particularly, to a pipetting device having an automatic mechanism for providing a new nozzle tip for each sample by fitting a disposable nozzle tip (hereinafter designated simply as a nozzle tip) to the lower end of the nozzle of the pipette. Thus, the automatic mechanism of the pipetting device enables one to provide a new nozzle tip to every new sample.
2. Background of the Related Art
Generally, when a minute amount of a substance in a sample solution is to be detected either by an immunological reaction or any other chemical or biochemical means, an appropriate reagent is added to the sample solution, a change provoked in the solution is detected and the magnitude of the change is measured for this end, skill is often required for the quantitative operations of measuring the sample solution and injecting the reagent solution.
Speaking generally, however, these operations are mostly so tedious and tiresome that troubles arise in handling minute amounts of sample and reagent solutions with a high accuracy and precision over extended periods. It is also desired to reduce the differences in the magnitude of errors between individual operations as much as possible. Further, the number of skilled operators falls far below the increasing number of samples. For these reasons, various investigations and developments have been made for automated devices by which determination and detection of minute substances can be performed by use of biochemical techniques.
As an instrument for the estimation of minute constituents in sample solutions, any automated apparatus must be capable of treating minute quantities of substances. On the other hand, when samples of different natures are to be estimated successively, where the concentration ratio of a substance between samples is up to 1:10.sup.6 (in the case of .alpha.-protein, for example), mixing of sample solutions in the apparatus should be minimized in order to attain high accuracy together with a low degree of error in the treatment.